Reginald h



Feb. 2, 1932. R. H. HAMILTON SELF ADJUSTING TAPPET Original Filed Jan.9. 1930 ATTORNEYS Reissued Feb. 2, 'i932 PATENT. OFFICE REGINALD H..HAMILLQON, OF, CHRISTCHURCH, NEW ZEALAND SELF ADJUSTING TAPPET vOriginal No. 1,786,237, dated'December 23, 1930, Serial No. 419,511, ledJanuary 9,!

Zealand November 1, 1929. Application `for reissue led July 2, 1931.

This invention relates to tappets by means of which intermittent one-waythrust motion l is communicated from a driving to a driven part, suchfor example as the tappets employed between the cam-shaft and thepoppet-valves of anengine.

It is well recognized that, to operate elliciently,tappets of this kindmust be of the exact length to fit between the said driving and drivenparts, with an allowable clearance, as in cases where la tappet is tooshort a certain amount of movement is lost and excessive' wear and noiseresult, while in the event of the tappet being too long the driven partis not permitted to fully return or reseat during the intervals betweensuccessive thrust impulses. A y

To maintain them in eiiicient condition therefore tappets requireadjustment from time to time to compensate for wear thatmust' inevitablyoccur in working surfaces. y

It isthe object of the present invention however to provide a tappet ofnovel and peculiar construction whereby the necessary adjustment of itslength will occur automati-v cally while the same is in use. In additionto its value in saving manual adjustment and promptly compensatingforany wear, or stretching, co-operatingparts,V the present inventionpossesses the further advantages that it automatically adjusts itself tocompensate for slight variations that may occur in the spacing of thedriving and driven partz-J due to temporary expansion and contraction ofthe metal as the result of variations of temperature.

. In carrying this object into effect according i to the presentinvention the tappet comprises essentially three members .formed withcorrespending internal and external screw threads whereby such membersare screwed `axially one within theother, the pitch of the said threadsbeing of suflicient coarseness to permit of their said screwing actionoccurring in response to endwise impulses upon such members, one of theinternal threads and its received external thread being right-handedwhile the other internal and external threads are left-handed.

that may occur in its 1930, and in New Serial No. 548,429.

In order that the nature of the invention and its construction may beclearly understood, it will now be fully described and explained withreference. to the accompanymg drawings, in which Fig. l is an elevationof atappet in accordance with the present invention together with itsco-operating driving and driven parts, the 'construction being hereshown partly broken away and in section to clearly reveal the internalparts and their arrangement.

Fig. 2 illustrates in perspective thecomposing parts of the tappet.

Fig. 3 is a somewhat similar View to that of Flg. lvshowing an additionto the construction, and,

Figs. 4, 5 and 6 are sectional elevations of the tappet and itscti-operating parts in more Aor lessdiagrammatic form illustrating itsself-'adjusting functions. t For the sake of illustratlng lts function,

the tappet is here shown as communicating the thrust action of a cam lto the stem 2 ofa valve operating against a valve-spring 3 in accordancewith the well known practice 1n internal-combustion engines.

The tappet is however equally adapted for use in other forms ofmechanism in which an intermittent one way thrust between a driving anda driven part is required;

In construction the tappet comprises a sleeve (1 having an internalthread 5 to receive a corresponding external thread 6 upon an invtermediate member 7 which latter is formed also with an internallythreaded axial bore 8 to receive a correspondingexternal thread 9 upon athird member 10.

One extremity 11 of the said intermediate member 7 at one end of thesleeve 4 constitutes one operative end of the tappet the other operativeend of which is constituted by a headv 12 upon the third member 10 atthe other or opposite end of the sleeve 4. p

The said threads are of sutil-cient coarseness to permit of the partsbeing screwed one within the other in response to impulses appliedend-wis'e to such members and'one pair of such threads is formed in theopposite direction to the other pair.

Thus, as here shown, the threads 5 and tendency beingJ preferablyattained by the 6 may be left-handed while the threads 8 and 9 are righthanded.

The third member 10, has a tendency to unscrew itself from theintermediate member, 7 thereby placing its head 12 atan interval fromvthe adjacent end of the sleeve 4, for a purpose hereinafter explained,such The said torsion spring is preferably ar` ranged also to actslightly in tension between its said connected parts.

Although other types of springs may be employed for this purpose 'atorsion-spring acting between the third-member 1() and the sleeve 4 ashere shown possesses the very important advantage that, in addition toimparting the required tendency to the third member 10, it serves alsoto keep all the threads in the correct bearing relation for theoperative action hereinafter explained, thereby avoiding any lost motionthat might otherwise occur in consequences of looseness the contact withthe driven in the threads due to wear or other causes.

The head 12 of the third member 10 is adapted to come in contact .withand frictionally engage its adjacent end of the sleeve 4, for whichpurpose such head is preferably formed with a tapered formation 14adapted to receive a corresponding tapered formation 15 upon the saidend of the sleeve.

' The tappet thus constituted is arranged as here shown, its end 11being operable upon `the driven part 2 and the head 12 being acted uponand under constant control by the drivlnv part 1.

If thought necessary or desirable also a piece of fibre or othersuitable substance may be inserted in a recess in the end 11 to receivepart 2 and thus reduce noise.

The sleeve 4 is mounted'to be capable of longitudinal reciprocationbetween such drivlng and driven parts, as` for example by arranglng itto slide within a tappet guide 16. Thelsaid sleeve may, when necessary,be restrained from axial turning by any suitable means, such for exampleas by the provision in the ta pet-guide-l of a feather 17 received 1n afeat er-way 18 in the sleeve. However, -when a torsion spring is used,this provision is unnecessary. Provision is made also for limiting thesaid movement kof the sleeve 4 towards the driving part 1, as for`instance by the provision upon the sleeve of an out-turned ange 19adapted to come in contact with the end of thetappet-guide 16 adjacentto the driven part.

The arrangement shown in Fig. 3 is identical with that already describedwith the addition of a second sleeve 2() having a closed end andarranged to slidably receive the sleeve 4 and head 12.

In this case the said sleeve 20 is itself slidably received in thetappet-guide 16 and the necessary restraint of the sleeve 4 againstvaxial turning is accomplished in any suitable manner, as by thevprovision in the sleeve 20 of a 'feather-way 21 to receive theaforemen-4 tioned feather 17 in the tappet-guide andthe provision in thesleeve 20 of a feather 22 to be received in the feather-way 18 of thesleeve 4.

In this case the driving part 1 acts upon the head 12 through thelnedium of the said closed end of the sleeve 20 and such end ispreferably arranged to frictionally engage the head for which purposethe latter`is preferably. formed with a tapered formation 23 tobereceived by a corresponding tapered formation 24 in the said end.

The operation is briefly as follows VVhen the'tappet comes to itsposition of rest. in the intervals'between successive operative impulsesfrom the 'driving part 1 to the driven part 2, its sleeve 4 is arrestedat a predetermined limit of proximity to the driving part 1 by its saidstop means, constituted as by the contact of the flange 19 with the endof the tappet guide 16.

- This arresting of the sleeve is arranged to take place'slightly before.the return of the driving part 1 is fully completed and vconsequentlyduring the remainder of .such return movement thethird member 10, owingto its aforementioned tendency, unscrews itself slightly from theintermedi ate member 7, thus4 placing its head 12 at an interval fromthe end of the sleeve, as shown in Figs. 1, 3, and 4, and in whichcondition the said threaded members are capable of movement in relationto one another.

When Athe parts are in this condition the third member 10 possessessomewhat greater resistance to movement into the intermediate member 7than does the latter to movement through the sleeve 4. i

When therefore the driving part 1, in commencing its operative movement,applies a thrust to the head 12 the third member 10 and intermediatemember 7 attempt to move through the sleeve towards the driven member. y

If the tappet ofthe correct length as in l Figs.v 1 and 3, this movement`will be frustrated by reason of the fact that the end 11 of theintermediate member is already in contact of the tappet being too greatto allow fof itsy ber7 throu ing the tappet r' 'd to slide through theguide v 'producing the required lengthening of the .ta pet.

n the event of the deficiency in the length being ful y made up in asingle movement as above explained, the adjustment willoccur pively asthe resultof two or more successive movements. t ere, however, a torsionspring is einployed to act between the sleeve 4 and the third member asdescribed, such spring will exert\ part 1. Y

In such cases therefore, in the event of the tappet being too short theaction of the said spring will move the intermediate mem! h the sleeve 4suiliciently to make up the d ciency immediately the head 12 dlsnsgtherefore the adjustment will occur immediately the ta pet assumes itsposition of rest and not as tige of the driving part 1, as previouslyexplained.

In either case however the intermediate member 7 being thus arrested bycontact withth driven part 2 the subsequent movement of the driving part1 causes the third member 10 to move into the intermediate member 7until the head 12 comes in contact and 'frictionally ges the end of thesleeve 4, thus locking botl: pairs'of threads and so renderand so conveye operative movement from the driving shownin Fig. 6. In the event ofthe ta pet being too long the driven art 2 will not returned orseatedwhen the eeve 4 is arrested by contact of its flange 19 with the endofthe tap t-guide.

Upon the sleeve being arrested an the head 12 disenga ing the sleeve 4therefore the pressure ofg the driven part 2 u n the end 11 foi-.cesthe`intermediate mem r into the 'sleeve until such driven member reaches itsfully seated position.` Y,

.In the case of the construction shown in 3, the functions of the tappetin len hen i or shortening to accommodate itse f to the riving anddriven parts will be identical with that already described. In this casehowever the` friction of the sleeve-20 with the head tends to reduce'the freedom ofthe latter to axial turning and so' serves to stabilizethe action of the member 10.

In `addition to this the interior of the sleeve 20 serves asanoil-container, thus en.-

suring a thorough lubrication of the internal.-

parts of the tappet independently of 'other sources. Y

' Again in cases where-the tap provided with an anti-friction ro ler orother special, formation to b e received by the drivconstant controlupon the interi` mediate member 7 tending to keep the end 1.1'-y

of the latter in contact with the driven a iicewith this invention willbe as correct and.

the end of the sleeve. In this case result of subsequent movement fthreaded bore,

. said third member actab part,l and meansy third member from saidintermediate memis to be.

that of aforesaid thi-ea ing-part 1, the said sleeve 20 affords a con. 1

vement means whereon such roller or forma.-i

tion may be mounted and serves also as a occur between the head -1,2 andthe end ofth'e sleeve 4whenthe tappet occu ies-its position of rest needbe no greater an may indeed be even lcjhan the customary clearanceallowed between a tappet of the ordinary kind and the driven part, sayone or more thousandthsof an inch', .andconsequently the self adjustmentprovided by a tappet-in accordmeans of which the third member adj u'stedtappets.i the ability to autoi matic ref adpistmeiit after ,eachoperative movement enables -,a .tappet in accordance with the presentinvention to compensate not gradual'e'ect of wear, but also v ,fortemporary changes in the spacing of the driving and driven parts due tovexpansion only for the and contraction of metals in consequence oftemperature variations, or other causes. Iclim: f 1. tappet comprisin acable longitudinally betveen a driven part, an internal ythread \in saidsleeve, an intermediate member having one end actable upon said drivenpart, said mem? .ber being formed with an external thread received insaid thread in the sleeve, an axial;

bore in said intermediate member havingan internal thread formed in theopposite direc'- tion to that of aforesaid threads, a third n ieiii-.part 1 .tothe driven part 2, as be h r aviiig an external threadreceived in said suicient coarseness to permit of said menibersibeingscrewed one `withiii the other in response to endwise a headupon i eupon by said driv ing part and adapted under pressure of the latter tocontact with said` sleeve, thereby toretain said threaded the adjacentend of sleeve ieciprc-y a driving and an of said threads being of partsrigid, stopmeansliii3iiting aforesaid movement of said sleeve towardsthe driving 'tending to` unscrew said termediate member having one endactable upon said driven part, said member being formed with an externalthread received in said thread in the sleeve, an axial bore in saidintermediate member having an internal thread formed in the oppositedirection to s, a third member.

havin an lexternal thread received in said threa ed bore, all of saidthreads being of sulicient coarseness to permit of said members beingscrewed one within the other in responseto endwise'impulses, a headuponsaidthird member actable upon by said driving part and adaptedunderfpressureof the latter to contact with the adjacent end of thesleeve thereby to retain said threaded parts rigid, stop-means limitingaforesaid movement of the sleeve towards said driving part, and a springtending to unscrew said third member from said intermediate memberthereby t'o. carry said head clear of the sleeve .to permit of'saidthreadedanembers re-adjusting' themselvesV to the requirements of said fdriving and driven Vparts when said sleeve is in contact with saidlimiting stop.`

3. Atappet comprising a sleeve reciprocable longitudinally between adriving and a driven partbut restrained from axial turning, an internalthread in said sleeve, an intermediate member having one end actableupon said driven part, said member being formed with an external threadreceived in said thread in the sleeve, an axial bore in saidintermediate member having an internal thread formed in the 'oppositedirection to that of aforesaid threads, a thirdv member having anexternal thread received in said threaded bore, all of said threadsbeing of sufficient coarseness to permit of said members being screwedone within the other in response to end-wise impulses, a head ,upon saidthird member actable upon by said vdriving part andadapted underpressure of the latter to'contact'with the adjacent end of 'said sleeve,thereby to retain said threaded.

'stop-means limiting aforesaid said sleeve towards the driving.

and a spring acting in torsion between said` leeve 'and said thirdmember and tending to unscrew the latter from said intermediate memberthereby to carry said head clear of said'sleeve to permit. of saidthreaded members re-adjusting themselves tothe requirements of saiddriving andv driven parts parts rigid, movement of part,

when said sleeve is in contact with saidlimiting stop.

4. A tappet as defined in claim 1 wherein a ,said sleeve isslidablewithin a'tappet guide 'and wherein said limiting stop isconstituted by an out-turned flange upon said sleeve adapted to come incontactnwith the end of said tappet-guide when said sleeve reaches apredetermined position of proXimitfv to said esv driving part. l

5. A tappet as defined in claim l wherein said head of the third memberis provided with a tapered formation to receive a corresponding taperedformation upon the end of the sleeve. Y v

6. A tappet as defined in claim 1 wherein said sleeve is slidably butnon-rotatably re, ceived within a second sleeve having a closed l drivenportions -ment and driven element, and means end to enclose the head ofthe third -member and provide a medium whereby the latter is acted uponby said driving part.

7. A tappet, comprising an internally threaded outer sleeve reciprocablelongitudinally between ya driving member anda driven member, anexternally threaded member disposed within and spaced from said sleeve,the .thread of said member being formed in the opposite direction fromthat of the sleeve, said inner member having at one end a head disposedin position to bel acted on by said driving member, an intermediatesleeve disposed between said outer sleeve and the inner member andhaving exterior and interior threads engaging the threads of Vsaidsleeve and inner member respectively, said intermediate sleeve havingmeans at one end thereof for actuating the driven member, `and meanstendin to un- Ascrevv"said inner member' fromsaid intermediate sleeve. i

8. In a valve operating mechanism, a driving element, a driven element,an adjustable vdevice therebetween'comprising driving and and meansoperative by a small but positive movement of said driving portion fromthe limit of travelof said drivmg portion toward said driving element tocause said adjustable ,device to become rigid and means for causing saidadjustable device to become freely flexible topermit lengthening orshortening of the same as soon as the valve seats.

9. In a `valve operating mechanism, a driving element,.a valve, a drivenelement operating said having a first portion adapted to engage saiddriving element, a secondportion adapted to engage said driven elementto transmit motion to said valve, a control portion adapted to engagesaid stationary member when the valve is seated and means controlled byengagement of said control portion and stationary member for lengtheningor shortening the tappet to fit between said driving elefor causing saidtappet to become, in eiect, a rigid unit when said control portiondisengages said stationary element.

10. vIn an adjustable device, a first contact memberv having oppositethreads, a control member engageable with one of said threads, la secondcontact member engageable with the other of said threads, ysaid contactmembers adapted to engage adjacent operating'elevalve, a stationarymember, a tappet alfri 'd `unit at times and to be -free to adjust.itslel between said adjacent operating elements at other times. p

11 In a tappet, a driving portion adapted to engage a driving element, adriven portion adapted to engage a driven element, a control ortionadapted toengage a lstationary memer near the limit of movement ofthetappet toward the driving element, saiddrlven porm tion having opposite.screw 'threads engageable, respectively, with mating screw threads l onsaid control portion and driving. portion, a spring acting between saidcontrol and driving portions urging said control and 1;, drivingportions apart, Aand clutch elements on said control and drivingportions disen` .gageable'when said control portion engages saidstationary member allowingI said spring to expand said control anddriving portions, said clutch elementsengaging when said driving portionis moved by said driving element a minute distance from the limit'oftravel of said driving portion toward said driving element to rigidlylock the parts of 2r 4the tappet together. 12; A tappet 'comprising asleeve reciprocable longitudinally between a driving and a driven part,an internal thread in -said sleeve,I an intermediate member having one:so end engageable with'said' driven partendhaving an external threadreceived in said sleeve thread, said intermediate member hav-A ing asecond thread of opposite direction to said first thread. a third memberengageable by said driving part and having a thread engaging said secondthread, all of said threads being of suliicient coarseness to permit ofsaid members being screwed one on the other in response to endwise im-40 pulses, said sleeve and third member having y clutch parts whichengage under force applied to said third member, thereby to retain saidthreaded parts rigid, a limiting stop for limiting movement of saidlsleeve toward said driving part to disengage said'clutch parts, and ahelical spring applying a turning movement between said sleeve and third`member, tending to unscrew said third member from said intermediatemember thereby 80 to disengage said cliitch parts to permit -of saidthreaded members re-adjustng themselves to the requirements of saiddriving and .driven parts when said sleeve is in contact with saidIlimiting stop. In testimony whereof I have hereunto aflxed my si ature.y I

R GINALD H. HAMILTON'.

